Koroush Taheri Talesh; Javad Yazdani; Amir Mohammadi; Azin Sohrabi; Aydin Sohrabi
Abstract
Introduction: It has been advocated that treatment of dentofacial deformities with jaw osieotomies may influence upper airway morphology, and several studies has shown that mandibular setback surgery has the potential to diminish airway size and alter the hyoid bone position.Objective: The purpose of ...
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Introduction: It has been advocated that treatment of dentofacial deformities with jaw osieotomies may influence upper airway morphology, and several studies has shown that mandibular setback surgery has the potential to diminish airway size and alter the hyoid bone position.Objective: The purpose of this study was to evaluate the effect of mandibular setback on the pharyngeal airway size, and hyoid bone position and to evaluate if a pre-surgical prediction on PAS can be made or not.Materials and methods: Twenty eight pre- and post-operative (3-4 months) lateral cephalograms of 28 individuals (16 females and 12 males older than 17) who had undergone vertical ramus ostetomy setback surgery to correct skeletal class III discrepancies. Cephalograms were traced and a paired-sample t-test was used to evaluate the difference between 11 linear variables pre- and post-operative measurements. Coefficient correlation was calculated for the amounts of setback and the change in airway size.Results: The vertical and horizontal position of hyoid and hyoid-mandible distance do not change significantly. Hyoid-2nd cervical vertebra and hyoid-pogonion distances reduced significantly. In the case of upper airway indicators, the width of pharynx was calculated at 4 different levels. In all 4 levels, statistical analysis revealed significant reduction but the correlation of reduction in the size of pharynx versus amount of setback is not significant (respectively from the most superior width to the most inferior one r=0.15, r=0.13, r=0.09, r=0.19).Conclusion: This study suggested that mandibular setback surgery can decrease the pharyngeal airway size.
Ahmad Sodagar; Allahyar Geramy; Ehsan Karimian
Hassan Hosseini Tudeshki; Mahnaz Arshad; Farnoush Mohammdi; Ehsan Mohamadian
Abstract
Aim: A complete knowledge of bone healing is a prerequisite to many decision makings in dentistry and is considered as a basic event in some research strategies. Any method that can accurately monitor the healing process is important to clinician providing the information required for further treatment ...
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Aim: A complete knowledge of bone healing is a prerequisite to many decision makings in dentistry and is considered as a basic event in some research strategies. Any method that can accurately monitor the healing process is important to clinician providing the information required for further treatment planning. Our study shows a simple and reliable method to evaluate the events that occur during socket healing in rats.Materials and Methods: Thirty five "Sprague - dawly" male rats were selected. All rats were anesthetized with intra peritoneal injection of Ketamin 10% and Xylazine 2% at the dose of 2 mUkg on day I. Mandibular left first molars were extracted with the use of very small excavator and hemostat forceps. At the same day,7,14,21,28,45 and 60 days after extractions, five rats were sacrificd, the left mandibles were removed and placed into 10% Formalinc. Muscles and gingival tissue were dissected away the Following day and the mandible was placed on a radiographic film and the buccul views were taken. The radiographs were scanned and analyzed with Avcnd (program that designed in matlab 6.1).Results: Increased density of the image of apical and crestal areas of the socket was observed on day 7. The maximum density of apical area was reached on day 28 and preceded towards crestal area on day 60. Density increasing in the crestal area is slower than apical area.Conclusion: Densitometrie evaluation of extraction socket healing using Avend program is useful and reliable to objectively assess bone formation and mineralization.
Tahereh Hosseinzadeh-Nik; Javad chalipa; Reza Jelodar
Tahereh Jalaly; Farzaneh Ahrari; Rasool Saheb Alam; Foroozandeh Amini
Abstract
Objective: In spite of the continuous interest of orthodontists in the effects of soft tissues on dental and skeletal structures, this influence is not well clear. The purpose of this investigation was to clarify the effect of open lip posture on selected dentoskeletal features of growing children.Materials ...
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Objective: In spite of the continuous interest of orthodontists in the effects of soft tissues on dental and skeletal structures, this influence is not well clear. The purpose of this investigation was to clarify the effect of open lip posture on selected dentoskeletal features of growing children.Materials and Methods: In this cross sectional study, 193 pupils (99 girls, 94 boys) with age range of 9 to 13 years were participated. All patients were examined by a trained investigator and those having incompetent lip seal were selected and their dentoskeletal features were compared with a control group consisting of 36 subjects with normal occlusion. The data were analyzed by independent sample t-tests.Results: Among the 193 students examined in this study, 19 cases (10%) were diagnosed as having lip incompetence. A more open lip posture was associated with an increase in overjet, lower incisor inclination and Palatal plane to Mandibular plane angle (p<0.05); while Interincisal angle was significantly decreased in this group compared to control subjects (p<0.05). The amount of overbite and upper incisor inclination were not statistically different between the two groups (p>0.05).Conclusion: The data from this study suggest that lip incompetence may have a significant environmental effect on dentofacial structures. Since lip seal assessment can be achieved simply by practitioners, parents or teachers, it is suggested that adults observe and provoke children to maintain appropriate lip posture.
Masood Feizbakhsh; Parvin Khadem; Peyman Torky; Sepideh Dadgar; Fatemeh Teimouri
Abstract
Aim: The main goal of thisstudywas to evaluate orthodontic treatment needs (IOTN) ofschoolboys population of Isfahan in 2009-2010based on Index of Orthodontic Treatment Need (IOTN).Materials and Methods: In this study an examiner used the Dental Health Component (DHC) and Aesthetic components (AC) of ...
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Aim: The main goal of thisstudywas to evaluate orthodontic treatment needs (IOTN) ofschoolboys population of Isfahan in 2009-2010based on Index of Orthodontic Treatment Need (IOTN).Materials and Methods: In this study an examiner used the Dental Health Component (DHC) and Aesthetic components (AC) of IOTN to assess Orthodontic treatment needs for 400 Isfahan schoolboys. Multistage randomized cluster sampling method was used to choose the participants. All the participants were schoolboys aged 11 to 14 years. Using the IOTN, Malocclusion was determined. To evaluate the data a chi-square test was carried out. Results: Taking into account DHC, 3.5% of Isfahan schoolboys were in 'Extreme need', 14% in 'Severe need', 25% in 'Moderate need', 38.5% in 'Little need' and 19% had 'No need' to orthodontic treatment.In evaluating AC, 77.5% had no need or little need, 16.5% had moderate need and 6% had great need to treatment group.Conclusion: It was concluded that 17.5% of 11-14 year-old male students in Isfahan need orthodontic treatment (IOTN grades 4 and 5) and common deviations in this group were impaction, hypodontia and contact displacement.
Allahyar Geramy; Amir Hooman Sadr haghighi; Seyed Amir Reza Fatahi Meybodi; Hasan Salehi
Abstract
Aim: Canine retraction is an important part of orthodontic treatments and should be coincided with preservation of posterior anchorage, The strain energy input of different appliance designs in teeth PDL is assessed.Materials and methods: Eight 3D finite element (FE) models of upper right maxillary molars ...
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Aim: Canine retraction is an important part of orthodontic treatments and should be coincided with preservation of posterior anchorage, The strain energy input of different appliance designs in teeth PDL is assessed.Materials and methods: Eight 3D finite element (FE) models of upper right maxillary molars and second premolar were designed. The models contained teeth, their PDL, and bone with their attachments. Combinations of wire cross scetion(round and rectangular), force application on the first or second molar, including or excluding the second molar, and adding the second molar to the system via ligature wire is considered in different models. The strain energy input to the PDL of different teeth was evaluated.Results: Engagement of all teeth, force application to the second molar resulted in 0.00017129 mJ and shifting toward applying force to the first molar resulted in 0.00017398 mJ. When the second molar was free from wire but laced; this energy finding was 0.00014499 mJ which increase to 0.0003991 mJ when the second molar was really out of the system. Findings for the rectangular wire were 0.00000084, 0.000001148, 0,0001026, and 0.0002929 respectively.Conclusion: Rotation prevention of the second molar is the key point in using its anchorage value.
Esfandiar Akhavan Niaki; Javad Chalipa; Davoud Abdollahi; Mohammad Moslem Imani
Abstract
Aim: previous designs like intrusion arch (Burstone) and Utility arch (Ricketts) to intrude anterior teeth in patients with deep bite had some advantageous, which required new consideration. The present study investigated new designs in making intrusion arch.Materials and Methods: PATRAN and NASTRAN ...
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Aim: previous designs like intrusion arch (Burstone) and Utility arch (Ricketts) to intrude anterior teeth in patients with deep bite had some advantageous, which required new consideration. The present study investigated new designs in making intrusion arch.Materials and Methods: PATRAN and NASTRAN programs were used in this computerized simulation study. Burstone, Utility arch designs; proposed methods i.e. A and B were loaded in 11 different cross sections and in 3 situations.
Result: the results indicated a lower load-deflection rate in newly designed intrusion arches and a more appropriate condition for implementation of a light continues forces .otherwise, the extent and the type of this placement in posterior blocks due to intrusion arch reaction, were in better condition in new designs comparing with those impervious ones.
Conclusion: Considering the advantages of the proposed designs it seems that their implementation would lead to better results in incisor teeth intrusion.
Maryam Poosti; Tahereh Jalaly; Farzaneh Ahrari; Samareh Mortazavi
Abstract
Aim: There are significant differences in morphological features of various racial and ethnic groups. The purpose of the present study was to identify cephalometric norms of Tweed diagnostic facial triangle in North East adolescents of Iran and to evaluate the effect of sexual dimorphism on cephalometric ...
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Aim: There are significant differences in morphological features of various racial and ethnic groups. The purpose of the present study was to identify cephalometric norms of Tweed diagnostic facial triangle in North East adolescents of Iran and to evaluate the effect of sexual dimorphism on cephalometric criteria of this population.Materials and methods: The sample comprised lateral cephalograms taken in natural head position of 40 pupils with normal occlusion (20 girls, 20 boys). Tweed diagnostic triangle was traced on each cephalogram and its angles were measured to the nearest 0.5°. The data were analyzed by SPSS software using independent samples t-tests and liotelling's test .Results: The lower incisors were significantly more proclined and mandibular plane was significantly steeper in north eastern Iranians compared to Caucasians (p<0.00 ). The average FMIA angle was significantly smaller than 65° as proposed by Tweed (p<0.001). There was no statistical difference in mean values of the three angles between boys and girls (p>0.05).Conclusion: There are significant differences in cephalometric norms of Tweed triangle between Iranians and Caucasians, showing important implications in orthodontic treatment planning. With respect to the significant differences in cephalometric norms of Iranians and Caucasians, it seems necessary to use standards of each racial group for orthodontic diagnosis and treatment of malocclusions in that population.
Amir Mohammadi; Saeid Foroughi Moghaddam
Abstract
Aim: Infectious complication which is reduced by chlorhexidine application may contribute to immediate orthodontic miniscrew failure. This study was determined to assess the influence of this agent on miniscrew immediate failure rate.
Materials and Methods: The study sample consisted of 62 miniscrews ...
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Aim: Infectious complication which is reduced by chlorhexidine application may contribute to immediate orthodontic miniscrew failure. This study was determined to assess the influence of this agent on miniscrew immediate failure rate.
Materials and Methods: The study sample consisted of 62 miniscrews inserted in 31 patients that their treatment plan consisted of placing one miniscrew on each side of their maxillary arch between first molar and second molar (2 screws for each patient). Fifteen patients were given a chlorhexidine regimen. Results: In the first six weeks after miniscrew insertion and before their loading 13.33 % of miniscrews in chlorhexidine group failed but the failure rate in non-chlorhexidine group was 6.25 %. According to Fisher's exact test the difference in failure rate was not statistically significant. Also there was no significant relation of failure rate to any category of the measured insertion torques or placement side (left or right) of miniscrews. Conclusion: Using chlorhexidine does not affect the miniscrew immediate failure rate. Also, insertion torque value and placement side (left or right side of the jaw) in the maxilla do not seem to have influence in miniscrew failure rate.
Ladan Eslamian; Kaveh Alavi; Sanaz Mehdizadeh
Abstract
Background and Aim: Conventional orthodontic treatment may affect on physical appearance and psychological aspect of patients. However, patient's attitude, expectations and self - concept influence the result of treatment. The aim of this study was to evaluate the expectations and self - concepts of ...
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Background and Aim: Conventional orthodontic treatment may affect on physical appearance and psychological aspect of patients. However, patient's attitude, expectations and self - concept influence the result of treatment. The aim of this study was to evaluate the expectations and self - concepts of patients referred to have orthodontic treatment to a private office and Shahid Beheshti, Dental School. Materials & Methods: To evaluate patient's expectations and self-concept, a questionnaire consisting of 13 close and 2 open questions was prepared. To determine whether the problems of patients are realistic, an orthodontist visited all patients and recorded the findings on a structured questionnaire. In addition some variables that might influence the score that patients recorded to evaluate their own dental esthetic were analyzed. To analyze the data, Chi-square, t test, ANOVA, Kappa statistic and multi-variable linear regression model were used.Results: Totally 252 individuals (92 males and 160 females) were evaluated. The most common orthodontic disharmony according to patient's view was irregularity in upper and lower front teeth (51.6%). Social problems were not common, but more than half of the girls sometimes had experienced shyness when laughing, due to their dental appearance. The patients' mean score to their own dental esthetic was 6.4±1.9, ranged from 0 to 10. This score was related to occlusion problems more than other variables.Conclusion: The patients did not diagnose their occlusion problems properly. Nevertheless they had not low self - esteem.
Barat Ali Ramazanzadeh; Mostafa Shahabi; Mohsen Merati
Abstract
Aim: Determination of overall and anterior Bolton ratios in people having normal occlusion in Iran and checking the effect of sexuality upon Bolton ratios in the aforementioned population and pinpointing the ability to apply normal quantities offered by Bolton in the Iranian population.Materials and ...
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Aim: Determination of overall and anterior Bolton ratios in people having normal occlusion in Iran and checking the effect of sexuality upon Bolton ratios in the aforementioned population and pinpointing the ability to apply normal quantities offered by Bolton in the Iranian population.Materials and methods: The study is a cross-sectional descriptive one by surveying study casts provided from 56 high school students (28 boys and 28 girls) having normal occlusions. Bolton ratios were considered in boys and girls separately. Statistical computations were conducted according to student t-test.Results: The total mesiodistal width of 12 permanent teeth and 6 anterior teeth in boys exceeded that of girls however this discrepancy has not statistically significant difference. The quantity of the overall and anterior Bolton ratios did not have statistically significant differences in boys and girls. The mean and standard deviation of the overall and anterior ratios in Iranian population were 91.58±2.03% and 77.73±3.17% which did not have statistically significant differences from the normal quantities offered by Bolton (P<0.05).Conclusion: The normal ratios offered by Bolton can be used in the Iranian boys and girls needing orthodontic treatments.
Mohsen Shirazi; E. Fakheri; Abdollah Afshar; M. Rahman
Abstract
There are few studies on the electrochemical corrosion behavior of Nitinol at various pH and temperature. Considering the pH of mouth can alter at a wide range, the present study investigated the effects of various pH and temperature of artificial saliva on the electrochemical stability of commercial ...
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There are few studies on the electrochemical corrosion behavior of Nitinol at various pH and temperature. Considering the pH of mouth can alter at a wide range, the present study investigated the effects of various pH and temperature of artificial saliva on the electrochemical stability of commercial equiatomic Ni-Ti orthodontic wire. In this manner, cyclic polarization tests were performed at different temperatures and pH. Surface conditions of wires were evaluated with Scanning-Electron Microscopy. Decreasing of pH to the acidic pHs and increasing of temperature in these pHs cause to increasing of Igor, and C.R. and decreasing of E, and Epit. The SEM micrographs indicate that the surface of sample become smoother after cyclic potentiodynamic tests. In fact, cyclic potentiodynamic tests cause to a general corrosion on the surface of sample. Corrosion behaviour of NiTi completely relies on the characteristics of its passive layer. Decreasing of pH causes to partly dissolution of the passive layer of NiTi in the acidic pHs. Influence of temperature on the corrosion behaviour of NiTi, related to the pH of solution. It appears that pitting critical temperature of NiTi in the artificial saliva is higher than 42 ̊C.
Allahyar Geramy; Tahura Etezadi; Ahmad Reza Shamshiri; Mohammad Javad Kharazifard
Abstract
Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical ...
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Introduction: An appropriate force system is a perquisite of desirable and predictable tooth movements during orthodontic treatment. Complete knowledge about the generated forces and moments by loops is essential to choose the best one for every situation.The aim of this study was to establish a mathematical equation to bring about a relationship between the L-loop height, width, activation and the produced force.Materials and methods: Six 3D finite element models were designed for L-loop without preactivation bends. Loops were designed with different widths (w) and heights (h). The cross section of wire was 0.016”× 0.022”. The distal end of each model was activated 1 mm in 0.1 mm intervals. The force produced by activation in a 0.1 millimeter increment was recorded. Results: Force findings were different according to the loop parameters defined. The produced force varies from 0.106 to 0.228 N for a 0.1 millimeter of activation and increased from 1.07 to 2.27 N in 1.0 mm of activation.Conclusion: The magnitude of force by L-loop can be estimated through adjustment of vertical part and activation as Increments of activation increased the delivered force while Increasing L-loop height decreased the generated force.
Gholamreza Shirani; Mahnaz Arshad; Sohrab Asefi
Abstract
Supernumerary tooth is a rare event, which is usually found coincidentally in radiographic examination. The prevalence of this event is 1-3% with different prevalence for primary and permanent dentition. Supernumerary teeth may cause various clinical problems including: delayed or failure of eruption, ...
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Supernumerary tooth is a rare event, which is usually found coincidentally in radiographic examination. The prevalence of this event is 1-3% with different prevalence for primary and permanent dentition. Supernumerary teeth may cause various clinical problems including: delayed or failure of eruption, displacement or rotation of permanent teeth and cyst formation.The purpose of this study was to present the case of a 9-year-old boy who had a large dentigerous cyst around his primary mandibular left premolar that was enucleated with the tooth. A year after this enucleation, we have observed a supernumerary tooth in mesial of canine. It is a reasonable question that “can the supernumerary tooth formation relate to the dentigerous cyst around impacted tooth?” Therefore, it is necessary to perform more pathological investigation in this aspect to answer this question.
Parviz Padisar; Mahtab Nouri; Elham Zajkani
Abstract
Aim: One of the core parts of clinical orthodontics is the analysis of dentofacial growth. Changes that occur in the shape, form and size of dentoalveolar arch may result in various problems during diagnosis and treatment planning. The aim of this study was to investigate the late changes of alignment ...
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Aim: One of the core parts of clinical orthodontics is the analysis of dentofacial growth. Changes that occur in the shape, form and size of dentoalveolar arch may result in various problems during diagnosis and treatment planning. The aim of this study was to investigate the late changes of alignment in the anterior teeth of mandible during 4-years follow up in young adults with normal occlusion in QazvinMaterials and Methods: This was a longitudinal descriptive survey with 23 samples (13 girls and 10 boys). Subjects with an age range of 13±1 were selected for dentoalveolar change assessment. Two dental models were prepared from each subject one at the start of the investigation and one at the 4 years follow up; photographs of each model were taken at the time. Inter-canine distance, anterior arch depth, arch shape index, anterior teeth width (6 anterior teeth), anterior arch circumference (ATSALD) were measured using AutoCAD 2004 software and digital caliper. Means and standard deviations were measured using Npar test analysis. Data were compared at 0 and 4 years and between two genders using Wilcoxon test (P<0.05).Results: The most prevalent changes in samples belonged to ATSALD (2.2mm increase) over the four years. The least changes were detected in arch shape index. Anterior arch circumference and ATSALD were the dominant changes in boys and girls, respectively.Conclusion: During this critical growth period, anterior crowding of mandibular teeth increases in both boys and girls, while the inter-canine distance and arch shape index decrease.
Fahimeh Akhlaghi; Elahe Vahid Dastjerdie; Payam Ghahari
Abstract
Introduction: Despite a substantial body of literature refuting an association between third molar eruption and crowding of the lower anterior dentition, the issue continues to be controversial. This study sought to assess the correlation between angulations of impact mandibular third molars and anterior ...
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Introduction: Despite a substantial body of literature refuting an association between third molar eruption and crowding of the lower anterior dentition, the issue continues to be controversial. This study sought to assess the correlation between angulations of impact mandibular third molars and anterior crowding of the lower arch.Materials and methods: 127 patients were examined in this analytical-descriptive study. Clinical and paraclinical records were obtained to assess different impaction angulations and the rate of crowding. Patients with history of previous extractions, orthodontic treatment, Bolton discrepancy and skeletal orthodontic malformations were excluded. Kruskal —Wallis test was used for statistical analysis.Results: Of the 127 patients studied, mcsioangular impaction was observed in 61 patients (48%). This study showed no significant correlation between different angulations of mandibular third molar impaction and crowding (P>0.05).Conclusion: This study seems to confirm that the role of the lower third molars is not a significant factor in causing late anterior crowding.
Javad Chalipa
Abstract
Aim: The goal of this research was examination of agreement between analysis of Hand wrist bones and cervical vertebrae to determine the skeletal age and patient’s growth value in 8-18 years of Iranian children referred to the department of orthodontics, faculty of Dentristy, Tehran University ...
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Aim: The goal of this research was examination of agreement between analysis of Hand wrist bones and cervical vertebrae to determine the skeletal age and patient’s growth value in 8-18 years of Iranian children referred to the department of orthodontics, faculty of Dentristy, Tehran University of Medical Sciences. Materials and Methods: A group of 123 subjects, in accordance with specific treatment design for these patients, performed right hand wrist and lateral cephalograms. Bones evolutionary stages of hand wrist examined based on Grave & Browns and Bjork methods in 9 phase and in 7 regions of hand and wrist. Evolutionary stages of cervical vertebrae determined based on Baccetti method by using from sight or aspect trunk of 2,3,4 vertabrae in 5 phase. These analyses repeated 6 month later. . Kappa Correlation index used for comparison of two used method in order to determine stage of skeletal maturity in general sample.Results: and Conclusion: correlation value in these two methods was weak to determine the skeletal age by analysis of Hand wrist radiography and cervical vertebrae. These cannot be considered as the alternate to determine skeletal age and growth peak with each other.
Azita Tehranchi; Hossein Behnia; Majid Heidarpour; Bahman Toutiaee; Mohammad Javad Khosropour
Abstract
Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees ...
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Aim: Analyzing the changes made during distraction osteogenesis (DO) in asymmetric mandibles.Materials and methods: This study was performed on a three dimensional model of a desiccated mandible, based on a finite element method. The distraction devices were placed with an angle of 90, 60 or 30 degrees to the oblique surgical cut. The directions of the pins were such that the 30 and 60 degree pins were placed in a counterclockwise direction relative to the perpendicular pin. The distractors were opened for 15 and 30 mm. The amount and direction of movement of proximal and distal segments and the displacement of pogonion were evaluated in all three planes of space.
Results: In the distal segment, the maximum change in pogonion was seen in 30 degree angle. In the proximal segment, if the distraction device was used with 90 degree angle, the condylar process rotated in the clockwise rotation. In 30 degree angle, this process rotated in a counterclockwise direction and the minimum rotation was seen in 60 degree angle.Conclusion: If gonial angle is to be augmented in a downward direction maximally, the angle of distraction device to the surgical cut is critically important (that is, it should be perpendicular to surgical cut). By use of perpendicular mode, ramus slops more posteriorly. It is better to use the distraction pin with a thirty degree angle if the ramus needs to be uprighted. The oblique surgical cut, irrespective of the distraction pin angle, increases the anterior facial height.
Mohammad Hossein Toodehzaeim; Hossein Aghili; Hoori Mirmohammadsadeghi; Elham Shariatifar
Abstract
Aim: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of Iranian (Yazd) population with that of the study of Tanaka and Johnston.Materials and Methods: Teeth on study casts of an unselected sample from a 11 to 25 years old (n 120; 60 males and 60 females) ...
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Aim: To compare the prediction of unerupted permanent canine and premolar size of a comparable sample size of Iranian (Yazd) population with that of the study of Tanaka and Johnston.Materials and Methods: Teeth on study casts of an unselected sample from a 11 to 25 years old (n 120; 60 males and 60 females) were measured in the mesiodistal dimension. An Iranian mixed dentition analysis based on the Tanaka and Johnston method was constructed with new linear regression equations for prediction of the mesiodistal widths of unerupted canines and premolars. Digital calipers were used to measure the mesiodistal widths of all teeth on study models fabricated from alginate impressions. The predicted widths of the canines and the premolars in both arches were compared with the actual measured widths.Results: Sexual dimorphism was evident between Iranian (Yazd) males and females in incisors, canines, and premolars in the mesiodistal dimension.Conclusions: To predict the space (in mm) required for alignment of unerupted canine and premolars in Iranian(Yazd) children, divide the sum of the mesiodistal dimensions of the four mandibular incisors by two and add the respective constants for males (upper, 12.91; lower, 10.51) or females (upper, 9.09; lower, 8.22).
Ali Tayebi; Farnoosh Fallahzadeh; Hamid Raji; Kazem Khosravi
Abstract
Introduction: One of the most important aspects of self-etching primer system in orthodontics is the duration of adhesive resin use after application of self-etching primer. Evaluating time delay effect on band strength is the objective of this study.Materials and methods: In this interventional-axperimental ...
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Introduction: One of the most important aspects of self-etching primer system in orthodontics is the duration of adhesive resin use after application of self-etching primer. Evaluating time delay effect on band strength is the objective of this study.Materials and methods: In this interventional-axperimental study, premolar with sound buccal enamel were selected, and randomly divided in four groups, In the first group buccal surface were etched for 30 seconds, with 37% phosphoric acid. After washing and drying, primer XT was applied on teeth and brackets. Transbond XT was used in bonding. Light with 500 mw was glowed from mesial, occlusal and distal surface for fifteen seconds, 5 and 10 minutes respectively. After thermocycling of all samples, debonding strength was measured with the help of DARTEC machine. Analysis was done by ANOVA and Duncan.Results: The highest shear bond strength (19.4 Mpa) was seen in group one and the lowest (9.87 Mpa) in group four. Between the remaining groups and group one, there was a significant difference in mean shear bond strength. Scan electron microscope showed a strong deep tag between tooth enamel surface and adhesive in group one.Conclusion: Significant difference in shear bond strength of two groups, traditional etching and self-etching primer was observed. Mean of shear bond strength with self-etching primer method was acceptable and delay in applying resin composite had no significant effect on shear bond strength of brackets to enamel.
Mehdi Hassanpour; Amirhossein Mirhashemi; Atefe Saffarshahroudi; Allahyar Geramy
Abstract
Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in ...
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Cone beam CT (CBCT) has become an increasingly important source of three dimensional (3D) volumetric data in clinical orthodontics since its introduction into dentistry in 1998. The purpose of this manuscript is to highlight the current understanding of, and evidence for, the clinical use of CBCT in orthodontics, and to review the findings to answer clinically relevant questions. It has therefore been recommended that CBCT be used in selected cases in which conventional radiography cannot supply satisfactory diagnostic information; which include cleft palate patients, assessment of unerupted tooth position, supernumerary teeth, identification of root resorption and planning orthognathic surgery. The need to use in other types of cases should be made on a case-by-case basis following an assessment of benefits vs risks of scanning in these situations.
Nasrin Farhadian; Amirfarhang Miresmaeili; Loghman Rezaei Soufi; Fahimeh Baghaei; Ehsan Shahvali
Abstract
Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method ...
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Aim: of this in vitro study was to evaluate the effects of Co2 laser irradiation on demineralization adjacent to orthodontic brackets and their shear bond strength in human premolar teeth. Enamel demineralization adjacent to orthodontic brackets is a major problem that requires new professional method independent to patient cooperation.Materials and methods: Sixty human premolars were randomly divided to two groups (n=30). Group1, enamel surface irradiated with Co2 laser. Group2 without any enamel surface treatment. In both groups, a bracket at buccal surface was bonded with Transbond XT and cured with conventional light cure. Demineralization in all sample induced with artificial caries solutions. A universal testing machine was used to determine shear bond strengths. The teeth were sectioned bucco-lingually and were evaluated under polarized light microscope. Average lesion depths were calculated from three depth measurements. The Two independent sample T- tests were used to compare the study type group in detail.
Results: The mean of shear bond strengths in the group1 and 2 were 13.90±5.01and 15.84 ±3.68 Mpa respectively, but not statistically significant (P=0.102).The mean lesion depth in group1and 2 was 72.29±58.09 µm 120.01±76.49µm respectively, which was significant (P=0.018).Conclusion: Co2 laser irradiation can reduce enamel demineralization while not affecting the shear bond strengths significantly.
Mohammad Hosein Ahangar Atashi; Reza Fekrazad; Leila Ebrabimpour
Abstract
Aim: The demineralization of enamel adjacent to orthodontic brackets is a clinical problem which can lead to some esthetic concerns after the treatment. The present study investigated the effect of laser, fluoride and combination of two techniques on the demineralization of enamel adjacent to orthodontic ...
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Aim: The demineralization of enamel adjacent to orthodontic brackets is a clinical problem which can lead to some esthetic concerns after the treatment. The present study investigated the effect of laser, fluoride and combination of two techniques on the demineralization of enamel adjacent to orthodontic brackets.Materials and Methods: In this in vitro study, 60 healthy human premolars were selected and the brackets were bonded to them. The specimens were randomly assigned to 4 groups (n=15): topical APF application, laser irradiation, Laser + fluoride and control specimens. Er,Cr:YSGG laser was irradiated at 12.5 mJ/cm2 pulse energy without water spray While APF gel was applied on the specimen surfaces for 4 minutes. All specimens were demineralized for 10 days in a 0.2M acetate buffer solution and the calcium content were subsequently determined with atomic absorption spectrometery. The data were subjected to analysis of variance and Tukey post hoc test.Results: The mean calcium content of specimens with APF fluoride application was 6.52±1.241 PPM, in laser was 6.66±0.64 PPM, in laser + fluoride specimens was 6.21±0.77 PPM and in control ones was 7.09±0.56 PPM, The calcium content of specimens subjected to laser irradiation and fluoride was significantly lower than control specimens (p=0.029), while no other significant differences were noted in the next comparisons.Conclusion: Er,Cr:YSGG laser irradiation does not increase acid resistance of enamel around orthodontic brackets with mentioned parameters, so, it is not recommended for clinical usage. Although, fluoride application following laser irradiation significantly increased acid resistance of specimens compared to control.
Amirfarhang Miresmaeili; Shahriar Shahab; Faezeh Yousefi; Vahid Mollabashi
Abstract
Aim: Tooth size in panoramic view has both magnification and distortion. It is supposed that panoramic view generated from Cone Beam computed tomography (CBCT) has more accurate tooth size compared with conventional panoramic view. The purpose of this study was to compare magnification of mandibular ...
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Aim: Tooth size in panoramic view has both magnification and distortion. It is supposed that panoramic view generated from Cone Beam computed tomography (CBCT) has more accurate tooth size compared with conventional panoramic view. The purpose of this study was to compare magnification of mandibular tooth size in digital panoramic radiographs andCBCT reconstructed panoramic images.
Materials and Methods: Amongpatients referred to Hamadan dental school, having both digital panoramic radiograph and CBCT, 28 patients were selected. Maximum width and length of mandibular teeth No. 36,34,33,31,41,43,44, 46 were measured in digital panoramic views and in CBCT reconstructed panoramic views. The CBCT images in multiple planes were used to give the dimensions referred to as gold standard. MANOVA test, Post Hoc and Tukey were used for statistical analysis.Results: There was a significant difference in width and length of teeth between digital panoramic view and both reconstructed panoramic view and gold standard (P value< 0.05). In digital panoramic view the maximum and minimum of magnification was observed in incisors and molar teeth respectively. There were no statistical differences in width and length measurements between reconstructed panoramic view and gold standard except for magnification in incisor teeth width (P value> 0.05). Conclusion: CBCT reconstructed panoramic views show significantly less magnification regarding tooth size compared with digital panoramic views.
